Octacalcium phosphate (Ca8H2(PO4) 6·5H2O, hereinafter sometimes referred to as “OCP”), which is a precursor of hydroxyapatite, has come into use as a synthetic bone material. To improve its moldability, OCP is usually used in the form of a complex with a polymeric material, such as alginic acid, gelatin (hereinafter sometimes referred to as “Gel”), or collagen. As bone regeneration materials comprising such a complex, for example, Patent Literature (PTL) 1 discloses a bone regeneration material comprising a dehydrothermally crosslinked co-precipitate of OCP and gelatin, and Patent Literature (PTL) 2 discloses a bone regeneration material comprising a complex of an OCP fine powder and gelatin.